Molecular Evidence of Structural Changes in Silk Using Unlimited Degradation Mass Spectrometry

Proteomics has important uses in archeological science
because
it can distinguish species, reveal the evolution of paleontology,
and provide biological evidence of historical events. However, this
technique still has full potential in the study of silk aging mechanisms.
In this work, we propose a strategy combining unlimited degradation
with mass-spectrometry-based proteomics techniques, which interpret
protein fragmentation propensity and secondary structure changes by
detecting content changes of specific peptide groups in complex proteomes.
This approach was employed to study the conformational changes in
silk microscopic crystals after heat treatment. Combining conventional
mechanics and crystallographic characterization, a thermal aging degradation
mechanism model was proposed. At the same time, it explained the interesting
problem that the crystallinity remained unchanged, but the mechanical
properties decreased significantly. Focusing on the unlimited degradation
process, this method will be widely applicable to the study of silk
and wool aging processes and regenerated silk fibroin.